WowAce

Adds a button to your character and inspect window that shows a summary of gear enchants and gems.

Provides a quick display for the LFG Call to Arms

Capital Cities NPC Browser

AltClick an item in your bag to add it a mail, auction, or trade frame, and alt-click to buy a stack if reagents.

Highly-configurable shield / absorb tracker.

Draws some lovely 3D portraits in the standard Blizzard artwork.

UnitActionBars2

Angry Raid Points Client

Lexan

Stable

Fudge

Automatically leaves the global channels when inside an instance/raid and restores them when exited.

Improved Quest Tracker

VisualThemes

A popup menu containing user-programmable scripts.

Adds manabars to the sides of Grid frames.

A module that lets you find out what today's dailies are without having to visit the quest givers.

TrapBar

Enables you to see Chinese, Japanese and other languages in game

Creates a broker plugin for all your broker launchers